1. Field of the Invention
The present invention relates generally to video signal recording and reproducing apparatus and, more particularly, to a video tape recorder having a built-in video camera.
2. Description of the Background
A device in which a video camera and a video signal recording and/or reproducing apparatus are combined in one body is known. To arrange and connect the various elements of the video tape recorder having a built-in camera, various techniques have been proposed, one of which is disclosed in Japanese Patent Laid-Open Gazette No. 54-86304, for example.
FIG. 1 shows a general circuit arrangement of such a combined camera and video tape recorder (VTR), which is mainly comprised of a camera section, shown within a one-dot chain line A, and a video signal recording apparatus section, shown within a one-dot chain line B.
As shown in FIG. 1, there is provided a camera circuit system or camera block 1, in which a signal derived from a charge-coupled device (CCD) imager element or an image pickup tube is amplified and processed in a predetermined signal processing manner to provide a luminance signal (Y) and color difference signals (R-Y) and (B-Y), which are sometimes referred to as I, Q signals.
A synchronizing signal generator circuit 2 uses a reference clock signal from a crystal oscillator 3 to generate a horizontal drive signal HD, a vertical drive signal VD, a color subcarrier signal of frequency fsc, a sampling clock signal having a frequency 4 fsc, horizontal and vertical blanking pulses, a burst gate signal, and a clamping signal. The horizontal and vertical drive signals HD and VD and the sampling clock signal of frequency 4 fsc are supplied to camera block 1.
The red R-Y and blue B-Y color difference signals from camera block 1 are supplied to an encoder 4, in which they are modulated in an orthogonal two-phase modulation fashion in response to the color subcarrier signal fsc supplied thereto from synchronizing signal generating circuit 2. Encoder 4 is also supplied with the vertical and horizontal blanking pulses P.sub.BV, P.sub.BH, the burst gate pulse P.sub.BG, and the clamping pulse P.sub.CL from synchronizing signal generating circuit 2.
A luminance/chrominance Y/C mixing circuit 5 mixes the luminance signal Y from camera block 1 and the carrier chrominance signal C from encoder 4 to provide an NTSC composite video signal suitable for display on a standard video monitor. This NTSC composite video signal is supplied at a monitor output terminal T.sub.M through a switch SW, whose operation will be described hereinbelow.
A record signal processing circuit 6 is of the generally known kind and the circuit arrangement thereof need not be described fully because it is well-known. In record signal processing circuit system 6, the luminance signal Y and the red R-Y and blue B-Y color difference signals from camera block 1 are processed to produce an analog component video signal suitable for recording on a magnetic tape. To be more specific, the luminance signal Y is frequency modulated to provide an FM-modulated luminance signal Y-FM, and the red R-Y and blue B-Y color difference signals, shown respectively in FIGS. 2A 2C, are timebase compressed and time-division multiplexed to provide a combined color difference signal, as shown in FIG. 2B. The combined color difference signal shown in FIG. 2B is then further frequency modulated to provide a color signal C-FM. The luminance signal Y-FM and the color signal C-FM are recorded on a magnetic tape T by magnetic record heads H.sub.R1 and H.sub.R2, respectively.
In the video signal reproducing apparatus section shown within the one-dot chain line block B of FIG. 1, the video signals Y-FM and C-FM that were recorded on the magnetic tape T according to the analog component recording system are reproduced from the magnetic tape T by playback magnetic heads H.sub.P1 and H.sub.P2, respectively. The reproduced video signals Y-FM and C-FM are then respectively amplified by playback amplifiers 10A and 10B and respectively demodulated by FM-demodulators 11A and 11B to provide the luminance signal Y and the complex chrominance signal C, whose timebase has been compressed, as shown in FIG. 2B.
The timebase-compressed/time-division multiplexed chrominance signal C is timebase-expanded by a timebase expanding circuit 12 to provide the two color difference signals R-Y and B-Y. A synchronizing signal separating circuit 13 is provided to extract a synchronizing signal from the luminance signal Y, and a pulse generator circuit 14 generates the various kinds of video pulses, such as horizontal and vertical blanking pulses and the like, on the basis of the synchronizing signal supplied thereto from synchronizing signal separating circuit 13.
Similar to encoder 4 of the camera section A, a playback encoder 15 converts the red R-Y and blue B-Y color difference signals supplied thereto into a carrier chrominance signal that is fed to a luminance/chrominance Y/C mixing circuit 16. In Y/C mixing circuit 16, the incoming luminance signal Y from FM demodulator 11A and the carrier chrominance signal C from encoder 15 are mixed to provide a composite video signal, and this composite video signal is fed out through the switch SW to the monitor output terminal T.sub.M. The switch SW is switched to a recording-side fixed contact REC when a cameraman takes a picture and to a playback-side fixed contact PB upon playback of recorded signals.
In the video tape recorder having a built-in camera constructed as described above, when in the recording or camera mode the camera section A and recording system are operated, whereas in the playback mode only the reproducing apparatus section B is operated.
Generally, the monitor output terminal T.sub.M is required to supply a composite video signal for NTSC playback or recording, so that the reproducing apparatus section B according to the analog component recording system must have its own encoder 15 for converting the component video signal to the composite video signal and must also have separate ones of the peripheral circuits related to the encoder.
Therefore, the built-in camera-type video tape recorder according to the analog component recording system must provide two encoders, one in the camera section and one in the reproducing apparatus section, which precludes a compact-sized apparatus and involves increased cost.